Pramana

, Volume 82, Issue 3, pp 585–605 | Cite as

Long term performance evaluation of the TACTIC imaging telescope using ∼400 h Crab Nebula observation during 2003–2010

  • A K TICKOO
  • R KOUL
  • R C RANNOT
  • K K YADAV
  • P CHANDRA
  • V K DHAR
  • M K KOUL
  • M KOTHARI
  • N K AGARWAL
  • A GOYAL
  • H C GOYAL
  • S KOTWAL
  • N KUMAR
  • P MARANDI
  • K VENUGOPAL
  • K CHANCHALANI
  • N BHATT
  • S BHATTACHARYYA
  • C BORWANKAR
  • N CHOUHAN
  • S R KAUL
  • A K MITRA
  • S SAHAYNATHAN
  • M SHARMA
  • K K SINGH
  • C K BHAT
Article
First Online:
Received:
Revised:
Accepted:

Abstract

The TeV atmospheric Cherenkov telescope with imaging camera (TACTIC) γ-ray telescope has been in operation at Mt. Abu, India since 2001 to study TeV γ-ray emission from celestial sources. During the last 10 years, apart from consistently detecting a steady signal from the Crab Nebula above ∼1.2 TeV energy, at a sensitivity level of ∼5.0 σ in ∼25 h, the telescope has also detected flaring activity from Mrk 421 and Mrk 501 on several occasions. Although we used Crab Nebula data partially, in some of the reported results, primarily for testing the validity of the full data analysis chain, the main aim of this work is to study the long term performance of the TACTIC telescope by using consolidated data collected between 2003 and 2010. The total on-source data, comprising ∼402 h, yields an excess of ∼(3742±192) γ-ray events with a statistical significance of ∼19.9 σ. The off-source data, comprising ∼107 h of observation, is found to be consistent with a no-emission hypothesis, as expected. The resulting γ-ray rate for the on-source data is determined to be ∼(9.31±0.48) h −1. A power law fit (dΦ/dE=f 0 E −Γ ) with f 0 ∼ (2.66±0.29) × 10−11 cm−2 s−1 TeV−1 and Γ ∼ 2.56±0.10 is found to provide reasonable fit to the inferred differential spectrum within statistical uncertainties. The spectrum matches reasonably well with that obtained by other groups. A brief summary of the improvements in the various subsystems of the telescope carried out recently, which has resulted in a substantial improvement in its detection sensitivity (viz., ∼5 σ in an observation period of ∼13 h as compared to ∼25 h earlier) are also presented in this paper. Encouraged by the detection of strong γ-ray signals from Mrk 501 and Mrk 421 on several occasions, there is considerable scope for the TACTIC telescope to monitor similar TeV γ-ray emission activity from other active galactic nuclei on a long-term basis.

Keywords

Cherenkov imaging technique TeV atmospheric Cherenkov telescope with imaging camera telescope Crab Nebula observation 

PACS Nos

95.55.Ka 95.85.Pw 29.40.Ka 
This is a preview of subscription content, log in to check access.

Notes

Acknowledgements

The authors would like to thank colleagues at the Centre for Design and Manufacture, the Electronics Division and Astrophysical Sciences Division of BARC who have contributed during the various stages of the planning, fabrication, installation and operation of the telescope. They would also like to thank the anonymous referee for making several helpful suggestions.

References

  1. [1]
    J Holder, Astropart. Phys. 39–40, 61 (2012)Google Scholar
  2. [2]
    F Aharonian et al, Rep. Prog. Phys. 71, 096901 (2008)Google Scholar
  3. [3]
    P M Chadwick et al, J. Phys. G: Nucl. Part. Phys. 35, 033201 (2008)Google Scholar
  4. [4]
    F W Stecker and O C De Jager, Ap. J. 476, 712 (1997)Google Scholar
  5. [5]
    E Dwek and F Krennrich, Ap. J. 618, 657 (2005)Google Scholar
  6. [6]
    F Aharonian et al, Nature 440, 1018 (1989)Google Scholar
  7. [7]
    T C Weekes et al, Ap. J. 342, 379 (1989)Google Scholar
  8. [8]
    A Daum et al, Astropart. Phys. 8, 1 (1997)Google Scholar
  9. [9]
    A M Hillas, Proc. 19th ICRC, La Jolla 3, 445 (1985)Google Scholar
  10. [10]
    D J Fegan, Space Sci. Rev. 75, 137 (1996)Google Scholar
  11. [11]
    G Mohanty et al, Astropart. Phys. 9, 15 (1998)Google Scholar
  12. [12]
    J A Hinton et al, New Astron. Rev. 48, 331 (2004)Google Scholar
  13. [13]
    O C de Jager et al, Ap. J. 457 253 (1996)Google Scholar
  14. [14]
    J Aleksic et al, Ap. J. 742, 42 (2011)Google Scholar
  15. [15]
    E Aliu et al, Science 334, 69 (2011)Google Scholar
  16. [16]
    A A Abdo et al, Science 331, 739 (2011)Google Scholar
  17. [17]
    R Ojha et al, ATel 4855 (2013)Google Scholar
  18. [18]
    G Aielli et al, ATel 2921 (2010)Google Scholar
  19. [19]
    B Bartoli et al, ATel 4258 (2012)Google Scholar
  20. [20]
    R Koul et al, Nucl. Instrum. Methods A 578, 548 (2007)Google Scholar
  21. [21]
    A K Tickoo et al, Nucl. Instrum. Methods A 539, 177 (2005)Google Scholar
  22. [22]
    S R Kaul et al, Nucl. Instrum. Methods A 496, 400 (2003)Google Scholar
  23. [23]
    K K Yadav et al, Nucl. Instrum. Methods A 527, 411 (2004)Google Scholar
  24. [24]
    M K Koul et al, Nucl. Instrum. Methods A 646, 204 (2011)Google Scholar
  25. [25]
    K K Yadav et al, Astropart. Phys. 27, 447 (2007)Google Scholar
  26. [26]
    P Chandra et al, J. Phys. G: Nucl. Part. Phys. 37 (2010), 125201Google Scholar
  27. [27]
    P Chandra et al, J. Phys. G: Nucl. Part. Phys. 39, 045201 (2012)Google Scholar
  28. [28]
    S V Godambe et al, J. Phys. G: Nucl. Part. Phys. 35, 065202 (2008)Google Scholar
  29. [29]
    S V Godambe et al, J. Phys. G: Nucl. Part. Phys. 34, 1683 (2007)Google Scholar
  30. [30]
    K K Yadav et al, J. Phys. G: Nucl. Part. Phys. 36, 085201 (2009)Google Scholar
  31. [31]
    R J Protheroe et al, Proc. 25th ICRC, Kruger Park, South Africa 8, 317 (1997)Google Scholar
  32. [32]
    A Konopelko, Astropart. Phys. 24, 191 (2005)Google Scholar
  33. [33]
    V K Dhar et al, Nucl. Instrum. Methods A 606, 795 (2009)Google Scholar
  34. [34]
    M Catanese et al, Ap. J. 501, 616 (1998)Google Scholar
  35. [35]
    T P Li and Y Q Ma, Ap. J. 272, 317 (1983)Google Scholar
  36. [36]
    A M Hillas et al, Ap. J. 503, 744 (1998)Google Scholar
  37. [37]
    F Aharonian et al, Ap. J. 614, 897 (2004)Google Scholar
  38. [38]
    A Konopelko, Astropart. Phys. 24, 191 (2005)Google Scholar
  39. [39]
    V K Dhar et al, Nucl. Instrum. Methods A 708, 56 (2013)Google Scholar
  40. [40]
    D J Fegan, J. Phys. G: Nucl. Part. Phys. 23, 1013 (1997)Google Scholar
  41. [41]
    A Tramacere et al, Astron. Astrophys. A 501, 879 (2009)Google Scholar

Copyright information

© Indian Academy of Sciences 2014

Authors and Affiliations

  • A K TICKOO
    • 1
  • R KOUL
    • 1
  • R C RANNOT
    • 1
  • K K YADAV
    • 1
  • P CHANDRA
    • 1
  • V K DHAR
    • 1
  • M K KOUL
    • 1
  • M KOTHARI
    • 1
  • N K AGARWAL
    • 1
  • A GOYAL
    • 1
  • H C GOYAL
    • 1
  • S KOTWAL
    • 1
  • N KUMAR
    • 1
  • P MARANDI
    • 1
  • K VENUGOPAL
    • 1
  • K CHANCHALANI
    • 1
  • N BHATT
    • 1
  • S BHATTACHARYYA
    • 1
  • C BORWANKAR
    • 1
  • N CHOUHAN
    • 1
  • S R KAUL
    • 1
  • A K MITRA
    • 1
  • S SAHAYNATHAN
    • 1
  • M SHARMA
    • 1
  • K K SINGH
    • 1
  • C K BHAT
    • 1
  1. 1.Astrophysical Sciences DivisionBhabha Atomic Research CentreMumbaiIndia

Personalised recommendations